Thermoelectric couple



Nov. 1.7J w25. 1,561,593 R. F. BROWN y THERMOELECTRI C COUPLE Filed Sept. 5, 1923 mvENToR l A' Far/mrd PE2-own,

Patented Nov. 17, 19254.

UNITED v'sT-AT Escl-m1* 511W oF FICE. y

v:inclinan r. BROWN, or PHILADELPHIA, rENNsYLvANIm- AssIGNon 'ro THE BROWN INSTRUMENT COMPANY, or ,rHILADELrHIa' PENNSYLVANIA, A conroaA'rIoN r`or PENNSYLVANIA.y 1 A applicatiol mea septeniber s, .1923. serial No. 661,041.

To all whom t may cofiwewt: Be it known that I, RICHARD P..BRWN,

. a citizen of the United States, and a resident electric couple; to provide a thermo-couple having an extension portion of low heat resisting materials combined with a p rimary portion of relatively 4hlgh heat resisting materials; to provide extensionleads for a thermo-couple whereby the cold junction of the couple is most accurately transferred to the measuring instrument, or to a point where the temperature vof the cold junction can be maintained constant; to provide a thermo-couple extension whereby a specific'electro-motive force is enerated i at a given temperature; to provl e a thermo-couple extenslon, one element of whlch is formed of an alloy of nickel, copper and manganese; .and to provide other lmprovements will hereinafter appear.

The drawing is a graphic representation of a thermo-couple embodying the present invention. Referring tothe draw1ng,one embodl- 1 ment of the 'present inventlon in thermocouple-extensions 1s' shown as a part of respective freeends joined at 13 an a'compound thermo-couple, having primary vmanganese has been stated as varying from one-quarter ofone per 'centto one per cent,

elements respectively" 10 and 11, 'oined in the usual manner at 12, and havm tlelr 1 to extension leads 15 and 16. The elementjl in the present construction is the positive element-of the cou le and' is formed of a nickel-aluminum al oy, and the element 11- is the negative element and is'formed of an alloy (f nickel and chromium, though it'will be un erstood 'that' the positive element of a couple isy the element from which the electric current ovvs to the other or negative element when the junctlon of the cou le is heated. Thus, the nickel-chromium w1rey is to be'connected .to the plus or positive side of the' measurmg instrument, while the nickel-aluminum w1re is to be connected ltothe negative side of the measuring instrument. These two alloys are widely used .as primary ,elements of a *thermo-couple THEBMOELEGTRIC COUPLE.

' because they' have a comparatively high heat resistance, a high electro-motive` force, and

produce Yan electro-motive force temperaturecurve with an absenceof critical polnts; "A prlma'ry thermo-couple as so constructedA is known. to the trade vas a chromel-a'lumel" thermo-couple, and has been selected as the preferred type of primary for use withthe extensions of the present invention,

though it-will .be understood thev invention is n ot limited to `this particular primary.

For the purpose of extending the cold junction of the thermo-coupleA to a distant point, such as a measuring instrument, 4or

a location Where the ytemperature `of the. cold junction can be maintainedconstant, the positive element 10 is connected toan, extension element wire-,1.5, formed of an alloy of nickel, copper and manganese, such alloy being enerally known as constantan.v

'The proportlons `of the-alloy are nickel, ap'- nroximately 45 .per cent; copper, approxi- `mately 53 percent; and manganese, from l@ per cent to 1 percent. The negative element 11, formed'of nickel and chromium, is i connected to a wire 16 -of copper of the purity of. the ordinary commercial copper wire. IThe materials of these extensions15 and 16 have considerably lessheatresistance but have the advantage of low resista-nce and the primary thermo-couple.

f than do the'primary elements of the couple,

j-While in the foregoing the p ercentageof i very desirable andsatisfactory. results, have beenobtained when the manganese content,- is one-half of one per cent, and this or asl nickel has a very material eiect on the .E, M. F. generated by a thermo-couple formed of constantan wire combined with a co perwire. For'` examplez a thermocoup e formed of constantan wire approximately 54 per cent, nickel approximately 45V per cent and manganese 1A of 1 per cent,

the other side of the thermo-couple being lo.

copper, with hot junction at 1500 F., col

junction zero F., will vea certain E. M. F.;

and if the copper an nickel in the constantan wire are maintained. 1n the Same proportions, and the manganese is increased to l of one per cent, thezcopper Wire remaining the same,a changein E. M. F. equiva lent to 150 F. will occur. Since achange 1n the manganese content from 1/1 of 1 per `cent to q'of one per cent causes a change ofA approximately 10 percent at 1500"- F.,and this percentage is approximately the 'same at 150 F., (the temperature to which the cold end of a primary thermo-couple may frequently be subjected), it is very.- impor- Ltant that in the manu-facture lof thermocold junctionfrom the thermo-couple to a distance by means of extension leads of copperv combined with a copper-nickcl-manganesealloy. The small percentage of impuri ties, such as iron, 'silicon and carbon remaining in the constantan wire 1n its finished state are negligible and have no effect upon the functioning; of the extension wires.

Although only a single form is shown inY which this invention ma be embodied, it is to be understood that tI e Vinvention is not limited to any specific construction, but might be applied in various forms Without departing from they spirit of the invention or the scope of the appended claims.

'Having thus described my invention, l claim: 4 v

1. A thermo-electric couple comprising in combination a primary couple and two extension elements thereto, one of said elements bein formed of an alloy containing approximately 54% of copper, approximately of nickel and from .25% to 1% of manganese.

2. A thermo-electric couple comprising in combination a primary couple and extension elements connected thereto, one of said elements'being formed of an alloy containing approximately 54% of copper, approximately 45% of nickel and approximately onehalf of one per cent of manganese.

-A thermo-electric couple comprising a primary couple having one element formed of nickel and chromium alloy and the other element formed of a nickel and aluminum alloy, 'an extension formed of pure copper connected to the nickel-chromium element, and a 'second extension formed of an alloy vcontaining approximately .54% of copper,

approximately 45% of nickel and from .25% to 1% of manganese connected to said nickel aluminum element. y

Signedat Philadelphia, county of Philadelphia, State of Pennsylvania, this 26 day of July, 1923.

RICHARD P. BROWN. 

